We're going to turn, now, to kansas city and that massive explosion you saw at the top of the show. It leveled part of a shopping complex in kansas city. Police, right now, are searching for any people who might still be trapped in the rubble. Abc's alex perez has been on the scene all night and joins us right now with the very latest. Good morning, alex. Reporter: Good morning, josh. And welcome back to, robin. Right here in kansas city, at least one person remains unaccounted for. And investigators are using cadaver dogs to help them comb through this debris. It was dinnertime when this explosion turned everything upside-down. Witnesses say the massive fireball, which engulfed an entire city block, could be seen for miles. The explosion, rattling windows blocks away. Everything shook. And it was -- you could feel it, almost as much as you could hear it. It was, by far, the biggest explosion I'd ever felt in my life. Reporter: Overnight, 100 firefighters worked to knock back the thick, black smoke and shooting flames, which forced onlookers to flee this kansas city shopping district just around 6:00 p.M. And injured more than a dozen. This was a happy hour at a restaurant. There were patrons in the restaurant. We're also concerned there may be additional people that were not able to get out of the structure. Reporter: This morning, investigators are trying to figure out what caused the blaze. But believe a contractor may have hit an underground natural gas line. We were grabbing our stuff. And the explosion hit. And it hits you like a shockwave. Reporter: Witnesses say gas fumes could still be smelled hours after firefighters got the flames under control. Again, at least one person remains unaccounted for. 16 other people were treated for their injuries. Authorities say, at this point, amazingly, there's no reports of any fatalities.

This transcript has been automatically generated and may not be 100% accurate.

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